Felt and drum assembly for drying webs



Dec. 23, 1947. L. HORNBOSTEL FELT AND DRUM ASSEMBLY FOR DRYING WEBS Filed March 20, 1944 r-zz E r1 c2":-

Zwro Hoe/vacancy.

Patented Dec. 23, 1947 FELT AND DRUM ASSEMBLY FOR DRYING WEBS Lloyd Hornbostel, Beloit, Wis., assignor to Beloit Iron Works; Beloit, Wis.

, consin a corporation of Wis- Application March 20, 1944, Serial No. 527,309

1 Claim. (Cl. 34-111) The present invention relates to means for heating and drying a web or sheet of paper or other material that is passing through an apparatus such as a paper making machine.

More particularly the invention relates to an assembly for absorbing moisture from and applying drying heat to the outer surface of a paper sheet trained around the Yankee drier drum of a paper making machine, although it is adaptable to other apparatus.

According to the invention the medium employed to apply heat to the sheet is a material having absorbent properties, such as a felt or the like, and means are provided to heat and dry-the material prior to contact with the paper sheet while the sheet is trained around other drying means that may comprise the drier drum of a paper making machine.

It is one of the principal objects of this invention to simplify the construction of a web-drying and heating assembly such as contemplated herein, and to improve the eillciency, operation and dependability of such assembly.

Another principal object hereof resides in the provision of a plurality of spaced drying units that are disposed radially around a drier drum and include loops of the material or other medium that is heated and dried on each unit before said material is brought into contact with the paper sheetv trained on said drum. This material in question may comprise a single band that is successively formed into outwardly disposed loops while traversing the drum with heaters at the loops. Alternatively, the material may comprise a plurality of bands each of which is formed in a separate loop with a heater that is individual thereto.

A further object is to provide a plurality of drier units outside the circumference of the drum, each unit being adapted to withdraw the web or band from the paper sheet on the drum, then heat and dry the web, and subsequently return the hot dry felt to the drum where it is engaged with the outer surface of the paper sheet. This sequence of operation is performed seriatim while the paper sheet is engaged and moving with a drier drum that is effective upon the adjacent surface of the sheet, and the arrangement is effective to an extent that the paper sheet has been com pletely dried before it is delivered or removed from the drum. A further object is to provide successively disposed means for applying drying heat to a paper sheet while said sheet is traversing a given path upon aunitary arcuate supporting member.

Another object hereof is to provide means whereby a heated and dry absorbent material is brought into surface contact, at a plurality of locations, with a paper sheet trained on a drier drum whereby the paper sheet is completely dried while it is trained around the drum. 1

A still further object is to providea plurality of strips of absorbent material, such as felt bands, that are each formed into its individual loop with a portion of such loop disposed in opposition to and moving with a drier drum so that such portions are engaged with the paper sheet that, is trained on the drum, In this connection, the separate felt strips or bands are heated while moving in their individual loops and out of contact with the paper or the drier drum, so that the absorbent properties of the material are enhanced and each feltwill arrive at the paper sheet in a hot and dry condition.

Additional objects, aims and advantages of the improvements contemplated herein will be apparent to persons skilled in the art after the construction and operation of the web drying assembly is understood with the within description. It is preferred to accomplish the objects of this invention, and to practice the same, in substantially the manner hereafter fullydescribed and as more particularly pointed out in the appended claim. Reference is now made to the accompanying drawings that are a part of this specification.

Figure 1 is a diagrammatic end elevation of an assembly that embodies the instrumentalities of the present invention.

Figure 2 is a diagram similar to Figure 1 showing a simplified form of the assembly.

It will be understood that the drawings are of a schematic character and that they disclose typical or preferred forms of the improvements contemplated herein. i

In its simplest aspect, the present improvements are exemplified in Figure 2 wherein the paper sheet 5 and the felt 6 carrying the sheet are trained around a guide roller 1. The felt and paper upon leaving this guide roller 1 pass into the nip between a pressure roller 8 that opposes the Yankee drier drum 9. At this nip the paper sheet leaves the felt by adhering to the drum. and travels on the drum throughout a major portion of the drum periphery. The paper strip 5 is removed from the drier drum 9 by means of the doctor ID that is engaged with said drum at the lower segment thereof. 1

While the paper is engaged with the surface of the drier drum 9, the present improvements contemplate the application of dry heat to the outer surface of the aper sheet, preferably at a plurality of segmental or arcuate areas throughout the circumference of the drum so that the web or paper sheet will successively enter said areas.

In order to perform the above mentioned function of applying heat and drying material to the exposed or outer surface of the paper sheet, an endless strip or band of suitable material ll having good absorbing properties, such as felt is employed in a manner so that the material is alternately engaged with the paper and then moved away from it, this action being successively repeated upon the paper sheet. A feed guide roller l2 directs the band of absorbent material or felt ll onto the exposed surface of the paper preferably at the lower segment of the drum and proximate the pressure roller 8 and outside the loop of the delivery felt 6. Prior to arriving at this feed guide roller l2 the felt has been trained in a loop l'la around a heated drier roller [3, said loop being formed between guide rollers l4 and I5.

A plurality of other heated drying rollers I6 are disposed in sequence and in spaced radial directions around the drier drum 9 to receive a plurality of other loops ll of the absorbent material or felt II. The felt is formed into these loops H by training it on guide rollers i8 and I9 that are close to the drier drum 9, the rollers i8 functioning to withdraw the felt II from the paper while the rollers l9 return the felt to the paper. The spaces between a roller l9 and the next roller 18 in the direction of travel of the paper sheetdefine areas where the heated diy felt is effective on the paper. These defined areas are arcuate in cross section and conform to the curvature of the drum circumference that supports the-paper.

After looping around each heated drier roller IS the felt returns to the outer face of the paper sheet and it will travel in contact with the paper until the felt reaches the next take-off guide roller I8 where it will be formed into the succeeding loop II. It will therefore be seen that the felt or other absorbent material leaves the paper several times during the travel of the paper in itsrotative movement on the drier drum 9, and each time the felt is withdrawn from paper contact it is heated and dried by a drying roller l6 and then returned to the paper to be effective thereon.

A withdrawing guide roller 20 is mounted adjacent the doctor to receive the endless band of felt II from the paper, and from this roller 20 the felt travels upon a series of outside guide rollers 2| that support it in a large return loop to clear the heating and drying assemblies while it is returning to repeat its cycle of operation at I the opposite side of the drier drum 9. At guide roller I 4 the felt again enters the first 100p Ila by engaging the drying roller l3 where it is heated and dried before it reaches the paper sheet. One of the outside guide rollers that support the large return loop of the felt is preferably a tension roller and is identified as 2Ia.

The structure shown in Figure 1 performs the same functions as the drying apparatus above described in connection with Figure 2. In Figure 1, however, the absorbent material that applies heat to and dries the paper sheet is not a continuous band, but it comprises a plurality of felt bands Ila each of which is trained upon the heated drying roller |6a by a plurality of guide rollers 22, one of which 22a may be a tension roller. The felt is engaged with the surface of the paper sheet by training it upon guide rollers 23 whereat the hot felt will engage the paper sheet and travel therewith until it has absorbed a considerable quantity of, if not all, moisture from the paper and it has assisted in the heating of the paper sheet. The individual felts H a are removed from contact with the paper sheet by training them over guide rollers 24 and intermediate guide rollers 22a may be employed as tension rollers for the individual felt loops.

From the above description it will be understood that the web to be dried travels with a heated rotatable drum that provides a heated arcuate support therefor, and while on this drum the web is. successively contacted by a plurality of runs of a felt or other moisture-absorbing material that has been heated and dried before engaging the web. The heating of the felt and the removal of moisture therefrom is effected by looping it away from the web and around heated rollers so that each successive run of the felt that is presented to the web provides a, freshly heated and dried cover therefor that has high moisture-absorbing property, As a result of this arrangement, the web becomes progressively drier not only because of its contact with the hot drum, causing vaporization of moisture, but also because moisture is sponged from the web by the felt covers which are hot and dry when applied to the web and which are removed from the web before the absorbed moisture therein can be transferred back to the web. Successive application of dry felt covers to the Web as it becomes drier prevents rewetting of the web and holding moisture therein.

It will, of course, be understood that various details of construction may be varied through a wide range without departing from the principles of this invention and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claim.

I claim as my invention:

A web drying apparatus comprising a main rotatable yankee drier drum for drying a web by contact therewith, drier felts for pressing said web against said drum, a plurality of felt drier drums positioned circumferentially about said main drier drum in spaced relation thereto, a plurality of guide rolls for training said felts against said main drier drum and against said felt drier drums, said felts respectively having arcuate runs on closely spaced, successive peripheral portions of said main drier drum of limited arcuate extent and means for transferring a web to be dried to the bare surface of said main drier drum for adherence thereto ahead of the point of first contact of any of said felts with said web.

-- LLOYD HORNBOSTEL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

